Our goal is the prevention of blindness and morbidity associated with inflammatory eye diseases, particularly trachoma and herpes simplex virus (HSV) infections. The studies proposed on trachoma will examine in detail the variations in host response to a single well characterized organism (Chlamydia trachomatis infection of the eye). It will allow us to evaluate response of the external eye to infection and the variations in disease that are intrinsic or induced (e.g. atopy or depressed cellular immunity. the grading of host repsonse (trachoma intensity) and microbial load (number of chlamydial elementary bodies) provide a quantitative system to study this interaction of host and environmental factors. In the studies of chlamydial infections we will (1) initiate studies on the role of individual host response to chlamydial infection; (2) elucidate the role of Chlamydia trachomatis as a cause of other illness in trachoma endemic areas; (3) evaluate new technology for the diagnosis of ocular chlamydial infections; (4) develop and validate simplified diagnostic techniques for endemic trachoma; (5) continue limited treatment trials for the prevention of blindness from trachoms. The major theme of these studies on trachoma will be an evaluation of the host response to infection of the conjunctiva. An important intermediate goal will be the identification of those host factors that are associated with the blingind consequences of trachoma. Herpes simplex virus and other infections of the eye continue to be a major problem, both in the United States and in other countries. Although treatment of ocular herpes has improved considerably in recent years, the disease continues to cause loss of vision and morbidity in many patients. In order to improve treatment of this disease by ophthalmologists, further refinements will be made in a computer model to provide treatment recommendations for herpetic eye disease. Similar models will be developed to give treatment advice in other forms of suppurative keratitis and for the treatment of eye problems by primary health workers in developing countries.